Synchronizing and phasing system for television recorders



7 Sheets-Sheet 1 July 22, 1952 R L GARMAN ET AL SYNCHRONIZING ANDPHASING SYSTEM FOR TELEVISION RECORDERS Filed Dec. 1, 1948 N MNNNDQNHSrmentors GAY/HOMO L. AQ/M/W JOHN K. mkf/voey v meg wwkbkm QSEBG QQEQMQ$83 6.

, July 22, 1952 R. L. GARMAN ET AL 2,604,535

SYNCHRONIZING AND PHASING SYSTEM FOR TELEVISION RECORDERS Filed Dec. 1,1948 v Sheets-Sheet 2 Zhwwtora 164 YMO/VD L. GAP/MAN ill 5 July 22, 1952R. L. GARMAN ET AL Filed Dec. 1, 1948 '7 Sheets-Sheet 3 136 133 134 141i 129 157 159 ourpur //VP(/T FIGURE 5 nbentors July 22, 1952 R. 1..GARMAN ETAL SYNCHRONIZING AND PHASING SYSTEM FOR TELEVISION RECORDERS 7Sheets-Sheet 5 Filed Dec. 1, 1948 B8 acw/v k, Mug

R. L. GARMAN ET AL July 22, 1952 SYNCHRONIZING AND PHASING SYSTEM FORTELEVISION RECORDERS Filed Dec. 1, 1948 7 Sheets-Sheet 6 SummonsHAY/146M!) A. GAE/QM July 22, 1952 R. L. GARMAN ETAL SYNCHRONIZING ANDPHASING SYSTEM FOR TELEVISION RECORDERS 7 Sheets-Sheet 7 Filed Dec. 1,1948 .NQQQNIN 3nbentors eAy/naA/a L. GAE/WW 8 JOHN K M A HYDE) tornegPatented July 22, 1952 UNITED STATES? PATENT FF E SYNCHRONIZING ANDPHASING SYSTEM FOR- TELEVISION RECORDERS RaymondL-Garman and John ,K.McKendry, Pleasantville, :N. Y., assignors to General .PrecisionLaboratory Incorporated, a corporation of New York Application December1, 1948, Serial.No.62',8.72': 1

16 Claims.

Thisinvention relates to a system" for syn chronizingand phasing-atelevision recorder to a television receiver.

In recording atelevision picture by a motion picture camera, a shutteris. required between the camera and the television picture screen fortwo reasons: The illumination must be .cut oif from the motion; picturefilm duringthe pulldown of the latter, and the duration of eachillumination must be exactly the duration-effor 1ev Maintenanceofcorrect timetelevision frame.

relations is therefore required between the shutter and the televisionreceiver and both synchronism and proper phasing are required."

between the shutter and the camera pulldown orintermittent mechanism. v

In the past it hasheen attempted to attain the'above objects .by the useof a mechanical shutter consisting of a perforated revolving disc placed.between thev television screen andthe camera, mechanically connectedwiththe camera intermittent mechanism so that ,synchronismv and.

proper phase between the two are maintained. The difiiculty has been inthe. maintenanceof each period of film illumination for exactly thelength of time of reception, of one video picture, equal to the timeaccording to present television standards of 525 horizontal scans orlines. Since the length of time required to exhibit'525 lines iscontrolled at the television transmittter it is not under controlof thetelevision receiver operator,- and it therefore is necessary to matchthe-illumination timepermitted by the disc to the periodof onetelevision picture. However, since thedisc illumination time at anyspeed is determined by the .size of holes in the disc, any change intheir size requires a change in the engineering design of the disc...Such .a change is of coursenotpossible during operation forautomaticaccommodation to momentaryr-changes .101. slow drifts in thetelevisionpicture transmissionfrequency, and so mechan-; ical shutteringhas; not been completely 'successful.

Electronic shutters are therefore particularly desirable becausedifficulties such as described,

can be overcome. However, in the use of elec-.

tronic shutters other diflicultieshave been encountered in synchronizingand phasing the.

shutter. with the camera intermittent and in synchronizing theshutter-with the television receiver.. Attempts to start or stoptheperiod ofillumination at the precise instant of initiationortermination of a television field of 262 lines have encountered the.difiiculty' of timing with enough precision to measure fractionallineswith high, accuracy. Such systems;:-.for..these and other reasons, havenot been successful; '1

The instant invention overcomes these. Idir-Y ficulties. It timesanelctrdnic shutterwiththe television receiver to permit each,illumination.

for exactly one television picture. of. 525.:1ine's'...

controlled bythe receiver itself and starting with the beginning-of theinitialline and-',.terminatingat the. endofflthe. 525th. line...Theinvention also utilizes synchronizing andipha'sing' signals generatedby the operationofithenshutteriand.

employs themv to. control. the, camera; so that all 'controlsfarise'.froinone primary,.soiirc.e;jthe..i. television equipment. These.-controls are. posi.-..,

tive and automatic'ginstantly accommodatingthef, I

operation of the shutter and"camera;v tofga y changes in. operationofthejtelevis'ion..equi ment. Any electronic shutter satisfyingfl theserequirements may beemployed in .Lthe'f instant;

invention such as, for example,.the,shutter. com.- prising a scale-ofl2sflcircuitj-described in the co:- pending application,

granted May 6, 1 52, of R. 1W; Lee et all.

The provision of a method and.-means,. for. synchronizing and phasingthe operationjof the.

camera with the shutter in television. recorders is one of the purposesof this invention.

The meansof synchronizing the; intermittent; I.

when the latter is operated by a motor ,.andt;a,, local electric powersupply, requires equipment for controlling the speediof. the".intermittent.

and means of phasing. requires .equimentlifon.

controlling its angular. ,displacement... These;

means must include provision for feeding. a. signal 1.

back from. the intermittent containing; phas'ee shift information, andmust aIs incIudeQa coin parator to comparethe feedback. signal with Tthereference signal. and. thereby... generatewa. can. rection signaL. The'comparatormaybe of any... typethat furnishes signals in thedsiredIfonn'.I-.. two. types being. described. hereinafterhas lex -q p Inintroducing synchronzing and phasing: core: rection rotations to the.cameraiintermittent, the

Serial No. ea'asaiifi id December 1, 19.48,now.-Patent..No.".2,595;397;'f'

3 from the following detailed description, considered together with theattached drawings in which:

Figure 1 illustrates a method of synchronizing and phasing a televisionreceiver shutter with a motion picture camera.

Figure 2 is a schematic diagram of the wiring of shutter switchequipment.

Figure 3 is a schematic wiring diagram of a scale-of-128 circuit.

Figure 4 is a schematic wiring diagram of a 12- cycle pip generator.

Figure 5 illustrates the introduction of a dif-- ference correctionthrough a mechanical difierential.

Figure 6 illustrates the introduction of a difference correction by arotatable stator.

Figure 7 illustrates the introduction of a difference correction byrotation of the camera motor field flux through use of a sinepotentiometer.

Figure 8 illustrates the introduction of a difference correction byrotation of the camera motor field flux with a tap switch.

Figure 9 illustrates the introduction of a difference correction byrotation of the camera motor field flux with an electronic converter.

Figure 10 illustrates the introduction of a difference correction byrotation of the phase of the electric power supplying the camera motor.

Figure 1 shows a television receiver 1 l with its cathode ray tube 12,the screen of which projects a real image through an optical systemrepresented schematically by lens 13 onto a specified area l4, occupiedintermittently by successive frames of sensitized motion picture film[6. This film is contained in a motion picture camera which, includingthe motor and the intermittent, is represented by the rectangle IT. Theshutter is not included in the camera but is separately represented by arectangle 18 as an electronic shutter acting upon the circuits of thecathode ray tube to blank it and to permit it to be illuminatedintermittently.

The camera I! is operated from commercial mains l9 which may be BO-cycleS-phase and may either be synchronized with those supplying thetelevision transmitter or not. If so, comparator equipment is necessaryto phase the camera; if not, the comparator equipment synchronizes aswell as phases.

In order to maintain correct synchronization and phase relationshipsbetween the shutter and the intermittent, signals or orders must betransmitted between them or from an outside source to both. In thepresent invention signals are transmitted to the intermittent. They maybe from any suitable source, but as an example the shutter is chosen asthe source generating the needed signals in addition to controlling thecathode ray tube. Since these signals are to convey synchronizationinformation to an intermittent which has a cyclic frequency ofapproximately 24 cps., the signal frequency maximum is inherentlylimited to this value. Since the shutter chosen as an example has acyclic frequency of one fifth of the frequency of the verticalsynchronizing pulses of the television receiver, or approximately 12cycles, this frequency becomes in this example the signal frequencytransmitted to the intermittent. However, any frequency equal to or lessthan that of the intermittent may be employed without departing from thespirit of this invention.

.' These phasing and synchronizing signals from the shutter 18, ledthrough conductor I29 to pip generator 21, cause the generation ofphasing pips at the cyclic rate of 12 per second. These pips are ledthrough the blocking condenser 25 to a comparator represented asenclosed in the dashed outline 23. Also a feedback signal consisting ofthe rotation of the intermittent shaft is fed back through rotatingshaft 30 to the comparator 23. As a result of the comparison of thesetwo input signals, the comparator 23 generates a signal representativeof the sense and amount of the difference between them, and transmits itthrough rotating shaft 56 to the camera in the following manner.

The feedback signals conducted into the comparator 23 through shaft 30operate a sinusoidal generator 26 which feeds the primary winding 21 ofa transformer 28 with a voltage having a frequency of approximately 12cycles. A secondary winding 29 feeds the resistors 3| and 32 in serieswith the rectifiers 33 and 34, with return through the resistor 35 to acenter tap, so that equal and opposite currents flow on alternate halfcycles and equal and opposite potential drops are thereby generated inthe resistors 31 and 32. The phasing signals are introduced throughconductor 40 to the transformer midtap, and therefore if positive willadd to the voltage of the terminal 35 if they occur during the halfcycleof current fiow through the rectifier 34, but will add to the positivevoltage of the terminal 31 if they occur during the other half-cycle,when the rectifier 33 conducts. If the pips occur at an intermediatepoint, the terminals 36 and 31 will be affected equally. As a result,the grid 38 of the triode 39 will be given a positive, negative or zeronet direct current potential in accordance with the phase of the pipsignal relative to the output phase of the generator 26, and thepotential of plate 4| and conductor 42 will be varied inversely. Thedevice thus sensitively detects and senses phase differences.

Phase differences as represented by divergences of the potential of lead42 above and below the zero signal value are made to correct the cameramotor phase and if necessary the speed as follows: A contact-makingarmature 43 is continuously vibrated by a solenoid 44 using anycommercial supply of frequency such as 60 cycles at leads 46, so thatthe armature makes contact alternately with fixed contacts 41 and 48,one on each side. The contact 48 is connected to lead 42 and the contact41 is energized by a battery 49 the potential of which is equal to theno-signal potential of lead 42. The armature 43 therefore, beingalternately excited by the potentials of the fixed contacts, attains aGO-cycle potential which is of zero amount when the two fixed contactpotentials are equal, and is of sensible amount otherwise, the phasewhen the contact 48 has the higher potential being 189 different fromthe phase when that contact has the lower potential. A two-phase motor5| has one field 54 energized in series with a condenser 57 by the samesource 46 that energizes the solenoid 44, the other field 53 isconnected through the conductor 52 to the armature 43. Consequently thephase of the field 53 either leads or lags that of the field 54 bydepending on whether contact 48 potential is above or below that of thecontact 41, and the motor 5! runs clockwise or counterclockwisedepending on the phase of the reference signal relative to that of thefeedback signal. The meton. shaft .56 is. connected t .th tc m te tocorrect. the intermittents fied in such sense as to,...ten.d to bringthe referen e. signal into the, center phase, .positionmelative. to thevfeedback signal.

The. electronic shutter I 8; is energized by both horizontal. andvertical, television synchronizing.

pulses secured from the. television receiver H through. conductors 35..and 5B. The shutterjflincludes switching controls. the schemat c wirinof which. isillustrated in Fig. 2, and a scale-oi: v

128.circuit, .with schematic wiring as illustra cd in Fig.3; Thesetwocircuits. are. Q e-fully .de-I

scribed in the. copending. application, Serial No.

62,832,.fi1ed on December. .1, 194 3;of,R. Lee

et .al.;' but are vsufficiently .describedior the pup. pose. of the.instantapplication as follows;

In Fig. .2. a. vertical pulseonconductor 58.;passes through cathode.followcntube, 59;.t0 trigger tube El, operating .a 11.0,00u s,multivibrator ,con.-.

sisting of, tubesv 62. and .63. Thisoperation, pro.-

duces a positivestepuf' potential... in conductor. 64 and in the screengrid of thepentagrid. tube.

66-, the control rid. .61. of. which is. kept. negative, preventingthepentode. from, conducting.v The next horizontal, pulse. however,.enters.

through conductor .and inverterfltube. 68., causing tube 66....toconduct momentarily and causing inverter amplifierwfiil to become nonconducting, producing a positive-pulse. in con-.-

This pulse energizes a sca1e of-.128 circuitillustrated in Fig.consisting of seven similar scale-of-two circuits in tandem;Theabove-mentioned positive pulse energizes the sc'a1e-of-128 circuitthrough conductor II and trigger .tube I2, loading thecathode' resistors13 and 14' and makingthecathode conductor H5 positive. As-

suming tube 11 initially conducting, it is madenonfcon'ducting and theplate. current flow of tube l8 is started, producing a negative pulseincond'uctor 1 9 However, the trigger tubes of tering on conductor 11; oe positive pulse is emitted on con uctor 88, and bein positiveca'uj'ses'purrent now in the cathode follower tube 89 and eeens uempositivelj output' pu e in conductor 9| which reenter's I the switchingc'ir cuitof Fig.2.

such positive 128th pulses are mixed with successive'v'ertical pulseginmixer tubes 92 and93, and the mixed series causes 'sharpp'ositive andnegative pulses to .be emitted by blocking oscillator tube. 94..

thirdlgridtolbe. positive, impressing negative pulseslon. diodes. 91.and 98 serving. asentrance valves to.a scale-ofrtwo circuit. consistingof the triodes .95 and ID I.

levels or steps of potential are transmitted hr gh mn ucwr. flz emnl er3; c ti de i 11Q e f.. 0. and u .0,. t a ode of .th television receivercathoderay tube. ,A

Wieresi ei rot c ielihus recsmii edh e ts The positive; peak.momentarily makes switch tube 95 conducting,.assumingfiits.

Their output therefore.con,. sists of two levels of..poten tia1v undercontrol ofv suucessive pulses irom switch, tube 5 an these 61'' he screes .-e-. esire(stee permits engine: tio n.

'Pe sfnemeih seeler ew wee -.99; nd-1 esl 'enel r ushie eduem 1 a d. sim has. etwel. e e9s1.. 289 eeeen s- The outcr steps of potential-ofthismultivibrator hree. nfine? of ti or. one periodpcorrspondmetolis h12.8 ben ene ees'ler e p ri d or'to the time of onefield /2 videopictur-etimel...

minus i'ZBQlines'L hese; alternative times; being employedcalternatelymhe outw S ps Z f- Poten a P t u ers alsqare} transmitted. throughconductor I29, to, the pig generatingicircuit 2i (Fig. '1).

his p r. s m nt n mm is st t d in Fig. 51. rneornmg qsitive vpulses.transmitted through difierentiating condenser] 36 and cathode follower.l3! energizes a scale-of-two circuit consisting of tubes [38 and I39.and half-ire.-

uenc lwlse e d i'fie te e ed my con n e clipped in tube .l4. and.pals'scdout' conductor Mqa posi ive. pulse 'to the ..co r1 iparatcr,Fig. 1.

These pu ses have a;, cyclic .jfre'quency bf v12, being one half oftheirequency. of the input pulses, at conductor I29 from ,the'outputterminaljof the hiitter- Big. '5 illustratesonemethod of introduction ofa correction signal to the intermittent. bymeans. of a. mechanicaldifferential for the purpose of.

Ph se enfl's e' li' emz ii t e t t e t a .jref erence signa1.. Acompara.tor. .l2l, which may be. of any type having mechanical feedback.

and automatically furnishings; mechanical phase cidrlredfioni sc -1such. a l-f fe ample, comparetorfI2i3 of Fig} "{1} receivesthroughconductor 40 ynchrcmzi g H and Phasing electrical reference.

signals from. any source. referred. in the final analysis to.shutterbperation. such as from the pip. generator 2| 'andshutter 18 ofFig. 1; and re"- shaft I I6 is driventhrough a mechanicaidiiferceivesmechanical shaft rotation 1' feedback sisnais. throu he shaft l la'and.the bevel gears Mandi l4 'from the Qintermittentshait is an ing I the?"intermittent. m; The] intermittent are aim e sfieee e n gse r m y thecamera synchronous motor. 1.21; whichis powered through. leads, .19.; bycommercial .power which.

may beBO-oyole, B-phiase .aiia 'neea. not be synchronizedwithg'the'itelevisionf transmitter or. shut er... he j hirq shaft 126'of the differential in .e ue ed. were ne sh m w or mparator 12 Ithroughwhichfthereis fui nish e d a correction, displacme'ntg and "ifYre qii iredga.- correctionspeedl n nie lbdiirere l einwdei ion nd.

subtraction devices, the. output displacement or.

rel l 22, at shaft: I21 will; be algebraic sum of the. input dis:

" l 7 from the,

p ments speedsiethsinput shaits izeanjd' one video picture. then to, be.blanked 7 I21, D is'that of input spider shaft I26 and D1 is that ofinput shaft I28. Other arrangements of the spider shaft may be used orother types of differential may be employed with appropriate changes inspeed reduction gear ratios and of directions of rotation.

Operation of the mechanism is as follows: Let it be supposed that themotor I24 operates at high speed so that the intermittent II1 operatesfaster than the speed which would synchronize the pulldown operationwith the shutter operation as represented by the signal received throughconductor 40. Generator 26 then operates at above-normal speed resultingin comparator 'operation as previously described rotating shaft I I9.This introduces a speed of rotation at shaft I26, which the differentialsubtracts from the speed of rotation of shaft I28, transmitting thedifference represented by the speed of shaft I21 to the intermittent andthrough shaft II8 to the generator 26. The latter thus having a speedreduced to or toward normal, reduces the correction signal at shaft E26to ortoward zero, so that the speed of the intermittent II'I becomes ortends to become normal, ultimately resulting in a speed approaching orhunting about normal to a closeness dependent on the effectiveamplification and damping of the comparator I2I and its feedback loop.

Figure 5 illustrates another embodiment of the invention wherein thefield of the synchronous motor driving the intermittent movement may bemechanically rotated in accordance with a reference signal so that theintermittent is properly synchronized and phased as respects the projecttelevision image. A comparator I2I as described in connection with Fig.5 is actuated by a reference signal through conductor It and'by thefeedback shaft I !8. Its output correction signal is transmitted as adisplacement or speed of its shaft I IE to a pinion I49. This pinion ismeshed with a gear I5I fastened to the stator structure of the camerasynchronous motor I52. The five slip rings I53 mechanically fixed to therotatable stator structure of the motor are required to conduct currentto the field and armature circuits and are in addition to the standardinternal rings of a synchronous motor (not shown). Any rotation of thestator of this motor must therefore rotate the field flux mechanically,and this ro- I tation will obviousl result in an increased speed ordisplacement of rotation of the motor output shaft I 54 if the directionof rotation of the flux is the same as that of shaft I54, or will resultin a decreased speed or displacement of rotation of the motor outputshaft I55. if the direction of rotation of the flux is opposite to thatof shaft W4. A differential control of the speed or displacement of theintermittent by'the comparator in accordance with'the synchronizing andphasing signal through rotation of the motor field flux, the motoroperating as an electromagnetic differential gear, is thus effected witha finalresuit as described in connection with Fig. 5.

Rotation of the field flux without mechanical rotation of the fieldstructure to introduce the correction signal to the intermittentrotation is shown in Fig. 7, employing a potentiometer. A synchronouscamera motor I56 drives an'intermittent I51 through a gear 23, afeedback signal at shaft II8 being compared with the reference signalreceived through conductor 49 by a comparator I2I and a correctionsignal being produced thereby as a rotation of shaft II9, all asdescribed in connection with Fig. 5. The motor I56, however, has heldwindings I58, I59, IGI and I62 in spatially two-phase arrangementbrought out to the four output terminals of a sine-cosine potentiometerI63 excited by a battery I64. The potentiometer shaft IE6 is attacheddirectly or through step-down gearing to the comparator output shaft II9, so that correction displacements or speeds of the shaft II9 willproduce in pairs of leads I61 and I68 potentials which will varyaccording to the sine and cosine, respectively, of the rotation of shaftII9. These potentials applied to windings I58, I59, IEI and IE2 producea rotating field flux in the motor I56 which is representative in sense,angular displacement and speed of that of the rotation of the shaft II9.This field displacement or speed will add to or subtract from thedisplacement or speed of motor shaft I59, and this addition orsubtraction is arranged to be in such sense as to tend to bring thefeedback signal frequency to an equality with the frequency of thereference signal, resulting in a synchronized and phased rotation of theintermittent.

A variation of this method of electrical rotation of the synchronousmotor field flux is illustrated in Fig. 8, employing a multipointswitch. A synchronous motor I1I drives the camera intermittent I51through the gear I23, and the speed and displacement of the feedbackshaft i 18 are compared by a comparator I2I with those of the referencesignal entering on conductor 40 as before described. However, the motorfield 12' is connected by numerous progressively positioned taps such asthe tap I13 with the terminals of a switch having two contact arms, I14and I16. This switch is shown functionally as surrounding the motor andwith the two contact arms as carried by a ring I11 having teeth I18around its periphery, a part only of which is here illustrated. A pinionI19 meshes with the teeth II'B'and the pinion I19 is driven through ashaft I8I by the motor 51 of the comparator I2I. Rotation of themotor-shaft I82 rotates the intermittent I51 and the feedback shaft II8.The comparator I2I compares the speed and displacement of the shaft II8with the speed and displacement associated with the reference signal andthrough the output motor 5I produces as a correction signal adisplacement or speed of the shaft ISI and the pinion I19. This rotatesthe switch yoke I11 so that a field excitation source diagrammaticallyillustrated by the battery I83 is connected through the brushes I14 andI16 to two opposite terminals of the field I12, the points of connectionmoving progressively around the motor magnetic structure in accordancewith the rotation of the pinion I19. As these points of introduction offield excitation rotate, the magnetic field poles are likewise rotated,and if the motion is in the same direction as the rotor rotation thelatter will be increased in amount to the sum of the two, or if themotion is in the opposite direction, the output shaft rotation will bethe difference of the two.

Another variation employing rotation of the synchronous motor field fluxis shown in Fig. 9. A different type of comparator is employed asillustration because the correction signal is required to be in aspecific electrical form, and any comparator producing a correctionsignal of this required form may be employed. The comparator of Fig. 9employs a converter such as described in copending application, SerialNo. 29,393, filed on May 26, 1948, now Patent No. 2,561,182, of RobertCrane, Jr. As before, a

verter tubes I93 and I94. is fed through conductors I96 and I9! to gridscamera synchronous motor I84 drives an intermittent I51 throughreduction gear I 23. A feed- I back shaft H8 drives a generator 26 theoutput frequency of which, representative of the speed and displacementof the intermittent, is to be compared with the frequency and phase of areference signal introduced at conductors I81. To facilitate initialadjustment of phase, provision for shifting the phase of either theintermittent cycle or the reference signal with respect to the other maybe made. For example, a mechanical differential I 86 may be insertedbetween the take-off point of the feedback shaft I I8 and theintermittent I51, or a phase-shifting network I88 may be insertedbetween the reference signal input conductors I81 and the converter.

The feedback signal is fed through conductors I89 and I90 to grids I9Iand I92 of tetragrid con- The reference signal I98 and I99 of the sametubes, but in conductor I91 there is inserted a. network which producesa 90 phase lag. This network may be of any type but preferably consistsof two coils 20I and 202 having mutual inductance and tuned by twocondensers 203 and 204 to the reference frequency. The tubes I93 and I94mix the signals and produce at conductors 206 and 201 output voltages ofsum and difference frequencies, with the phase of the voltage inconductor 20! leading or lagging that of conductor 206 by 90, dependingon which of the two input voltages is of higher frequency. The voltageson conductors 208 and 201 are applied to the grids of cathode followertubes 208 and 209 and the transformed outputsare-applied to'fieldwindings 2H and 2I2 of the motor I84. These windings are mechanicallyarranged to be magnetically 90 apart, so that when excited by slowlyalternating electrical power through conductors 2 I3 and 2 I4, with one.leading the other by 90 in phase, a continuous field flux rotation willbe produced with the direction of rotation dependent on which fieldvoltage lags. Condensers 2 I6 and 2 I1 cooperate with the fieldinductances to pass the difference frequency to the fields and to drainoil the sum frequency through the condensers to ground. The cathodereturns and cathode resistors of tubes 208 and 209 are arranged so thatpotentials of conductors 2I3 and 2| 4 will be varied'by equal amountsabove and below ground. The combination of field flux motion with normalsynchronous motor rotation of the rotor will produce modi fi'ed rotationof the intermittentas described in connection with Fig. 5.

In feedback amplifier arrangementsa residualerror usually exists. Thismay be minimized in the present case by eliminating the reductiongearing I23, interposing a frequency converter 23I'between the (SO-cyclepower supply and the synchronous motor, thus reducing the frequency of.the latter to approximately that of the intermittent, and of courseemploying a. motor I84 built for that frequency.

A third embodiment ,of the invention is-v shown in Fig. v in. whichtheflsynchronizingand phasing correction difference signal is introducedbe- -tween the .unsynchronized power supply andthe synchronous cameramotor. The motor 22I drives anintermittent I51 through a gear I23,

anda feedback shaft I I8 enters a comparator I2 I,

.which may be as described in connection with Fig. 5. The comparatorcompares thefeedback signalwith a reference signalentering through aconductor 40 and producesacorrection signal and athree-phase rotor 228.;The phase of the output conductors 221 will then be progressivelychanged with respect to the phase of the input conductors connected topowermains by rotation of rotor 226 through shaft 222, and thisphasechanging, if continuous, of course amounts to a changeof-frequency. The phase and frequency changes thus produced by thecorrection-signal introduced through shaft 222 are made to be of suchsense as-to tend to bring the frequency and phase of the feedback signalin shaft 8 and of the cyclic-operationoftheintermittent I51 to be thesame as those of the reference signal, asdescribed in connection withFig. 5.

What is claimed is: a

1. A synchronizing and'phasing system for a television recordercomprising, a television receiver including a cathode ray tube for thedisplay of the received 'televisionimages on the screen thereof,electronic shutter means actuated by the receivedtelevisionsynchronizing-signals for periodically blanking said cathoderay tube screen, a motion picture camera including an intermittentactuating a sensitized filmstrip, means for projecting the images formedby the illumination of said cathode ray tube screen on said film strip,means operated by said intermittent for producing a first signal,means-operated in'accordance with actuation of said shutter meansproducing a second signal, comparison means operated by said first andsecond signals having as an output an error signal whose amplitude andsense is a function of the departure in phase relation between theblanking ofsaid cathode ray tube screen and. the operation of saidintermittent and means for altering the speed andangular displacement ofsaid intermittent in accordance with the amplitude and sense of saiderror signal.

2. A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray tube screen are- -successively projected on a'sensitized film strip comprising, an electronicshutter operated by the received television synchronizing signals *forperiodically blanking saidcathode ray tube screen, an intermittentincluding a-driving means for periodically advancing said sensitizedfilm strip, means operated by signals derived from said electronicshutter for producing a first signal Whose phase corresponds totheperiodic blanking ofsaid cathode ray tube screen, means operated bysaid intermittent for producing a second signal whose phase correspondsto the periodic advancement of said film strip, means forcomparing thephase of said first'andsecond signals and forproducing an" error signalfrom said comparison-whose amplitude and "senseis a function of thedifference in phase between said first and second signals, and means-foraltering the operation of said driving means-in accordance with theamplitude and-sense of said error signal. H

3. A synchronizing and phasing system fora television recorder whereintelevision images formed on a cathode ray tube screen are successivelyprojected on a sensitized film strip comp i an electronic shutteroperated by the received television synchronizing signals forpcriodically blanking said cathode ray tube screen,

an intermittent including a driving means for periodically advancingsaid sensitized film strip, a first signal generator operated by signalsderived from said electronic shutter generating a first signal bearing adefinite phase relation to said periodically receiving blanking periods,a second signal generator operated by said intermittent driving meansgenerating a second signal bearing a definite phase relation to theperiodic operation of said intermittent, comparison means connected tocompare the phase relation between said first and second signals and forproducing an error signal which varies in accordance with the relativephase relation of said first and second signals, and means for alteringthe operation of said intermittent driving means in accordance with saiderror signal.

4. A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray'tube screen are successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forperiodically blanking said cathode ray tube screen, an intermittentincluding a driving means for periodicallyadvancing said sensitized filmstrip, a first signal generator operated by signals derived from saidelectronic shutter generating a first signal bearing a definite phaserelation to the periodically recurring blanking periods, a second signalgenerator operated by said intermittent driving means generating asecond signal bearing a definite phase relation to the periodicoperation of said intermittent, a phase detection circuit connected tocompare the phase relation between said first and second signals and forproducing an error signal having an amplitude intermittent driving meansin accordance with the operation of said motor.

5. A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray tube screen are successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the re ceived television synchronizing signals forperiodically blanking said cathode ray tube screen, an intermittent forperiodically advancing said sensitized film strip, a motor driving saidintermittent, a first signal generator operated by signals derived fromsaid electronic shutter generating a first signal bearing a definitephase relation to the periodic blanking periods, a second signalgenerator operated by said intermittent driving'motor generating asecond signal bearing a definite phase'relation to the periodicoperation of said intermittent, a phase detection circuit connected tocompare the phase relation between said first and second signalsproducing an error signal whose quality is dependent onthe phaserelation between the first and second signals and means operated by saiderror signal for rotating the field fiux of said interinittent drivingmotor whereby said intermittent is maintained in phase and synchronismwith said blanking periods.

6, A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray tube screen are successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forpcriodically blanking said cathode ray tube screen, an intermittent forperiodically advancing said sensitized film strip, a motor driving saidintermittent, a first signal generator operated by signals derived fromsaid electronic shutter gen crating a first signal bearing a definitephase relation to the periodic blanking periods, a second signalgenerator operated by said intermittent driving motor generating asecond signal bearing a definite phase relation to the periodicoperation of said intermittent, a detection circuit connected to comparethe phase relation between said first and second signals producing anerror signal having a sense and amplitude dependent on the phaserelation between the first and second signals, a motor operated in onedirection or another dependent on the sense of said error signal andmeans controlled by said motor for rotating the field fiux of saidintermittent driving motor.

7. A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray tube screen are successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forperiodically blanking said cathode ray tube screen, an intermittent forperiodically advancing said sensitized film strip, a motor, drivingmeans connected between said motor and said intermittent, a first signalgenerator operated by said electronic shutter generating a first signalhearing a definite phase relation to the periodically recurring blankingperiods, a second signal generator connected to said intermittent and0,.- erated thereby to generatea second signal bearing a definite phaserelation to the periodic operation of said intermittent, means forccrnparing the relative phase relation of said first and second signalsand means operated by said last named means for maintaining a saidintermittent in synchronism and constant phase re lation with saidblanking periods.

8. A synchronizing and phasing system atelevision recorder whereintelevision images formed on a cathode ray tube screen are succesivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forperiodically blanking said cathode ray tube screen, an intermittent forperiodically advancing said sensitized film strip, a motor, driving:means connected between said motor and said intermittent, a first signalgenerator operated by said electronic shutter generating a first signalbearing a definite phase relation to the periodically recurring blankingperiods, a second 5 3 genera-tor connected to said second intermittentand operated thereby to generate a second signal bearing a definitephase relation to the operation of said intermittent, a phase detectioncircuit connected to compare the phase relation between said first andsecond signals and producing an error signal having an amplitude andsense dependent on the relation between said first and second signals, amotor operated by said error signal and means interposed in saidintermittent driving means between said first mentioned motor and saidintermittent for altering the operation of said intermittent inaccordance with the operation of said second mentioned motor.

9. A synchronizing and phasing systemaccordz ing to claim 8 in whichsaid means interposed 13 in said intermittent driving -meanscomprises adifierential having a first input shaft operated by said first mentionedmotor, a second input shaftoper'ated by said second mentioned motor andan output shaftconnected to operatesaid intermittent.

10. A synchronizing and phasing system'fora television recorder whereintelevision images formed on a cathode ray tube screenare successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forpcriodically blanking said cathode ray tube screen, an intermittent, asynchronous motor connected to operate said intermittent, a source ofalternating current supply for said synchronous motor, a first signalgenerator operated by said electronic shutter generating a first signalbearing a definite phase relation to the periodically recurring blankingperiods, a second signal generator operated by said intermittentgenerating a second signal bearing a definite phase relation to theperiodic operation of said intermittent, means for comparing therelative phase relation of said first and second signals and meansoperated by said last named means for varying the phase of thealternating current supply for said synchronous motor whereby theintermittent driven by said synchronous motor is maintained insynchronism and constant phase relation with said blanking periods.

11. A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray tube screen are successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forpcriodically blanking said cathode ray tube screen, an intermittent, asynchronous motor connected to operate said intermittent, a source ofalternating current supply for said synchronous motor, a first signalgenerator operated by said electronic shutter generating a first signalbearing a definite phase relation to the periodically recurring blankingperiods, a second signal generator operated by said intermittentgenerating a second signal bearing a definite phase relation to theperiodic operation of said intermittent, a phase detection circuithaving impressed thereon said first and second signals producing anerror signal whose sense is dependent on the relative phase relation ofsaid first and second signals and means operative by said error signalfor varying the phase of the alternating current supply for saidsynchronous motor whereby the intermittent driven by said synchronousmotor is maintained in synchronism and constant phase relation with saidblanking periods.

12. A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray tube screen are successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forperiodically blanking said cathode ray tube screen, an intermittent, asynchronous motor connected to operate said intermittent, a source ofalternating current supply for said synchronous motor, a first signalgenerator operated by said electronic shutter generating a first signalbearing a definite phase relation to the periodically recurring blankingperiods, a second signal generator operated by said intermittentgenerating a second signal bearing a definite phase relation to theperiodic operation of said intermittent, a phase detection'circuithavingimpressed thereon said first and second signals producing an errorsignal whosesense is dependent on the relative phase relation of saidfirst and second signals, a motor operated in one direction or anotherin'response to the sense of said error signal and phase shifting meansoperated by said last mentioned motor connected in circuit between saidalternating current supply source and said synchronous motor whereby theintermittent driventhereby is maintained in synchronism and constantphase relation with said blanking periods.

13. A synchronizing and phasing system for a television recorder whereintelevision images formed on a cathode ray tube screenare-successivelyprojected on a sensitized film strip comprising, an electronic shutteroperated by the received television synchronizing signals forperiodically blanking said cathode ray tube screen, an intermittent, asynchronous motor driving said intermittent, a first signal generatoroperated in accordance with the received television synchronizing signalgenerating a first signal bearing a definite phase relation to theperiodically recurring blanking periods, a second signal generatoroperated by said intermittent generating a second signal bearing adefinite phase relation to the periodic operation of said intermittent,means for comparing the relative phase relation of said first and secondsignals and means operative by said last named means for rotating thefield flux of said synchronous motor whereby the intermittent driventhereby is maintained in synchronism and constant phase relation withsaid blanking periods.

14. In a television recorder system wherein television images formed ona cathode ray tube screen are successively projected on anintermittently actuated film strip, the method of operation whichcomprises, generating blanking signals from the received televisionsynchronizing signals and utilizing said signals to periodically blankthe cathode ray tube screen, generating a first signal bearing adefinite phase relation to said blanking periods generating a secondsignal bearing a. definite phase relation to the intermittent actuationof said film strip, comparing the phase relation of said first andsecond signals and utilizing said comparison to alter the periods ofintermittent actuation of said film strip to maintain synchronismbetween the movement of said film strip and said blanking periods.

15. In a television recorder system wherein television images formed ona cathode ray tube screen are successively projected on anintermittently actuated film strip, the method of operation whichcomprises, generating blanking signals from the received televisionsynchronizing signals and utilizing said blanking signals topcriodically blank the cathode ray tube screen, utilizing said receivedtelevision synchronizing signals to generate a first signal bearing adefinite phase relation to said blanking periods, generating a secondsignal from the actuation of said film strip bearing a definite phaserelation to the intermittent actuation thereof, comparing the phase ofsaid first and second signals, producing an error signal from saidcomparison and utilizing said error signal to correct for departure fromsynchronism between said blanking signals and the intermittent actuationof said film strip.

16. The method of photographing a television picture on anintermittently advanced film strip which comprises, periodically andrecurrently shuttering the television picture, producing a signalrepresentative of the speed and phase of the recurrent shutteringperiods, producing a signal representative of the speed and phase ofactuation of the intermittent mechanism, comparing said first and secondmentioned signals, producing a correction signal as a result of suchcomparison and correcting the speed of the intermittent by saidcomparison signal.

RAYMOND L. GARMAN.

JOHN K. McKENDRY.

REFERENCES CITED The following references are of record in the file ofthis patent;

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